Address Book Lookup - First & Last Name

At the risk of showing my ignorance, I just stumbled across something quite new to me in using the lookup feature in the Contacts on my T600: if you type the first letter of the contact's first name, and the first letter of the last name, it will perform the lookup and filter the list by that criteria. In other words, typing "RS" will get you everyone with those initials. I had been a Treo 300 user for a year before getting the 600 last month and never noticed this function on that device either. Sorry if everyone knew this, but thought I'd pass it on in case there were some like me who didn't.